WASHINGTON — The Supreme Court struck another major blow against long-standing restrictions on campaign money Wednesday, freeing wealthy donors to each give a total of $3.6 million this year to the slate of candidates running for Congress.

Rejecting the restriction as a violation of free speech, the 5-4 ruling struck down a Watergate-era limit that Congress wrote to prevent a single donor from writing a large check to buy influence on Capitol Hill. It was the latest sign that the court's conservative majority intends to continue dismantling funding limits created over the last four decades.

FOR THE RECORD:Supreme Court: An article in the April 3 Section A about the Supreme Court's latest campaign finance decision identified an attorney representing Senate Minority Leader Mitch McConnell in the case as Robert Burchfield. His name is Bobby Burchfield.

Under those limits, donors could give up to $5,200 to any individual candidate for Congress per election cycle, and no more than $123,200 to all candidates and political party committees put together.

Acting on an appeal from the Republican National Committee, the high court left the individual candidate limits intact but declared the overall limit unconstitutional.

As a result, individuals will be able to give the individual maximum to every candidate for Congress, either directly or through contributions to a political party. That in effect raises the new maximum that can be given to candidates and party committees during a two-year election cycle to $3.6 million.

Though Republicans cheered the decision and Democrats denounced it, both parties stand to gain, although Republicans somewhat more so.

"No matter how desirable it may seem, it is not an acceptable government objective to 'level the playing field,'" he said.

Campaign finance experts said the ruling's importance was less about its immediate impact — fewer than 700 people in the last election cycle bumped up against the aggregate limit, according to the Center for Responsive Politics — than what it suggests about where the court is headed. The ruling stands as Act II in the decline and fall of the campaign funding laws, and strongly suggests another act is in the offing.

Four years ago, in the Citizens United decision, the court freed corporations, unions and the very wealthy to spend unlimited sums independently on election campaigns. The struck-down limit had stood since 1947.

The ruling led to the creation of "super PACs," the name given to the political action committees that could collect millions of dollars from undisclosed donors to fund campaign ads.

Wednesday's decision, which came as parties are gearing up for the midterm election this fall, may involve less money, but it allows donors to have a more direct impact on lawmakers because it will allow contributions directly to their campaigns rather than through outside groups.

"If the court in Citizens United opened a door, today's decision may well open a floodgate," Justice Stephen G. Breyer said in a dissent read in court. "It creates a loophole that will allow a single individual to contribute millions of dollars to a political party or to a candidate's campaign."

"Where money calls the tune," Breyer said, "the voices of the people will not be heard."

The next limit likely to come under attack, campaign finance experts said, is the restriction on contributions to state political parties.

Roberts and the court's conservatives say the government can put limits on money only to prevent "corruption" that is akin to bribery. The law "may not seek to limit the appearance of mere influence or access," the chief justice wrote.

That narrow definition of corruption "will be significant in future campaign finance cases" because it eliminates a major argument that had been used in the past to uphold restrictions, said Robert Burchfield, who represented Senate Minority Leader Mitch McConnell (R-Ky.) in the case.

UC Irvine law professor Richard Hasen said the court's opinion "takes a big step closer to gutting the last bits of campaign finance reform."

The decision, McCutcheon vs. Federal Election Commission, also shows again the impact of President George W. Bush's two appointees: Roberts and Justice Samuel A. Alito Jr.

A decade ago, the court upheld the campaign finance law McCain-Feingold in a 5-4 decision joined by then-Justice Sandra Day O'Connor. Chief Justice William H. Rehnquist, while a conservative, had said corporations did not have free-speech rights in politics. But after Roberts and Alito replaced Rehnquist and O'Connor, the court had a 5-4 majority to void election laws that restricted the role and influence of corporations and the wealthy.

Though the legal dispute was fought out as a 1st Amendment matter, the case had a clear partisan flavor. The Republican National Committee and McConnell urged the court to strike down the aggregate limit on contributions, and they won with the votes of the five justices who were Republican appointees — Roberts, Alito, Antonin Scalia and Anthony M. Kennedy.

Justice Clarence Thomas agreed with the result but wrote a separate opinion saying the court should overrule the Buckley vs. Valeo decision of 1976 and void all limits on campaign contributions.

Obama administration lawyers defended the limits, arguing they worked to prevent the very wealthy from having undue clout on Capitol Hill. The four Democratic appointees agreed with them, with Justices Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan joining Breyer in dissent.

Defenders of the campaign funding laws were outraged. Fred Wertheimer, a veteran champion of campaign finance reform, said the court was on a "march to destroy the nation's campaign finance laws enacted to prevent corruption."

The decision "re-created the system of legalized bribery today that existed during the Watergate days," said Wertheimer, president of the nonprofit group Democracy 21.

Michael Waldman, president of the Brennan Center for Justice at New York University Law School, said neither the Founding Fathers nor most Americans "want government beholden to narrow elite interests."

Republicans called those concerns overwrought.

In the last two-year election cycles, outside groups such as super PACs, trade associations and so-called public welfare organizations spent $1.3 billion, many times more than candidates and political parties.

Compared with that, the amount wealthy donors will now be able to add will be marginal, said Benjamin Ginsberg, a leading GOP election lawyer.

The current campaign finance system is upside down, Ginsberg said, because outside groups can raise and spend unlimited amounts of money, whereas candidates and political parties face tight restrictions. In many races, spending by outside groups now dwarfs what the candidates can spend.

"The candidates are afterthoughts and they should not be afterthoughts," he said, adding that the court's ruling would even the playing field only slightly.

Although Democrats decried the ruling — Rep. Nancy Pelosi (D-San Francisco), for example, called it "misguided and destructive" — it's not clear how much advantage the Republicans will get from it. The donors who hit the contribution limit in the last election cycle favored Republicans over Democrats, but both parties have developed very effective fundraising efforts.

Officials from both parties predicted the ruling would accelerate fundraising efforts in the run-up to the fall election, when Democrats are fighting a Republican effort to wrest control of the Senate.

Matt Canter, deputy executive director of the Democratic Senatorial Campaign Committee, said the decision would "significantly boost our efforts to keep control of the Senate."

The broader impact may be to further entrench the influence that certain industries have over both parties. A study by the Sunlight Foundation found that of the top 1,000 donors to campaigns in the 2012 elections, more than one-third worked in finance, real estate and insurance.

"This is not a decision that advantages one party over the other," said Sen. Charles E. Schumer (D-N.Y.). "It's a decision that advantages the very wealthy over everybody else."